The present invention relates generally to an imaging apparatus alignment system and method and, more particularly, to a system and method for aligning the image beam of an imaging apparatus of the type which may be used in an automated media exchanger.
An automated media exchanger is a device generally comprising a media library, a media handler, and media players. The automated media exchanger stores media, e.g., digital linear tape cartridges, in the library. When the information contained on a particular piece of media is required by a user, the media handler extracts the media from the library, transports the media to a media player, and inserts the media into the media player. The media players are devices that convert the media to a usable format, e.g., the media players may be digital linear tape players as are known in the art. The automated media exchanger may also include an imaging apparatus affixed to the media handler wherein the imaging apparatus is used to identify the media. Bar codes that identify the media may, as an example, be affixed to the media and the imaging apparatus may be adapted to read the bar codes to identify the media in a conventional manner.
The library typically comprises a plurality of media magazines. The magazines are generally parallelepiped structures comprising a plurality of slots or openings that are adapted to hold the media. A user may fill the magazines with media and then the user may place the magazines into the library within the automated media exchanger. There is generally some tolerance between the magazines and the structures supporting the magazines in the media library, thus, the media may be located at imprecise locations relative to the automated media exchanger. Furthermore, the magazines may abut each other within the library, which creates additional tolerances that add to the imprecision in the location of the media. These tolerances accumulate to create a tolerance stack between the location of the media and the automated media exchanger. The location of the media relative to the automated media exchanger, thus, becomes more imprecise as the tolerance stack increases.
The process of moving media from the library to a media player involves moving the media handler to a position adjacent to a specific piece of media in a magazine. The media handler then moves to extract the media from a specified slot in the magazine where the media is held. The media handler then moves adjacent to a specified media player and inserts the media into the media player. Likewise, the media handler may extract media from a media player and insert the media into a specified slot in a magazine by reversing the above-described procedure. The insertion and extraction of the media into and out of the magazines and the media players requires that the media handler precisely contact the media. If the media handler does not precisely contact the media, damage may occur to the media, the library, the media handler, and the media players.
The imprecise location of the media relative to the media handler creates problems when the automated media exchanger moves media into or out of a magazine or a media player. For example, the imprecision impedes the ability of the media handler to quickly insert and extract media into and out of a magazine and a media player without the risk of damaging components in the automated media exchanger. In order to precisely contact the media, the media handler may have to slow down to orient itself relative to the media prior to contacting the media. The media handler may, as an example, have to physically sense the location of the media in order to orient itself, which increases the operating time of the automated media exchanger.
These problems may be partially resolved by aligning the previously described imaging apparatus, which may be affixed to the media handler, to the slots in the magazines and to other components in the automated media exchanger. An example of aligning an image beam associated with the imaging apparatus to the magazine slots, the media players, and other components in the automated media exchanger is described in the U.S. Patent application, Ser. No. 09/291,242 of Gardner et al. for GUIDANCE SYSTEM AND METHOD FOR AN AUTOMATED MEDIA EXCHANGER, concurrently filed herewith, which is hereby incorporated by reference for all that is disclosed therein.
Even when the image beam associated with the imaging apparatus is aligned to the components in the automated media exchanger, however, it is still possible that the media handler itself may not be properly aligned to these components. This improper alignment may be due to misalignment between the image beam associated with the imaging apparatus and the media handler. As previously described, proper alignment between the media handler and the magazine slots, and thus, the media, is critical in order for the media handler to successfully extract media from the magazine or to insert media into the magazine. Proper alignment between the media handler and the media players is also critical for media exchanges between the media handler and the media players.
Misalignment between the media handler and the aforementioned components may, for example, be caused by misalignment between the image beam associated with the imaging apparatus and the media handler, which may, in turn, be caused by variables in manufacturing or in assembly of the imaging apparatus and the media handler. Accordingly, although the alignment system and method of application, Ser. No. 09/291,242, previously referenced, enables the image beam associated with the imaging apparatus to be accurately aligned to the magazine slots and the media player, it is further necessary to align the image beam to the media handler in order to ensure that the media handler accurately aligns with the magazine slots and the media player.
Therefore, a need exists for an alignment system that will align the image beam associated with an imaging apparatus to the media handler to which the imaging apparatus is affixed.
An alignment system that aligns an image beam associated with an imaging apparatus is disclosed herein. The imaging apparatus may, as an example, be a bar code reader as is known in the art. The alignment system determines the transverse and vertical positions of the image beam relative to the imaging apparatus or relative to a structure supporting the imaging apparatus. The alignment system may comprise an alignment target of a predetermined size located at a predetermined position relative to the imaging apparatus. The imaging apparatus images the alignment target and performs an analysis based on the image of the alignment target to determine the position of the image beam relative to the alignment target.
The alignment target may comprise a first edge and a second edge, wherein the first edge and the second edge define boundaries of reflective difference. A first axis, constituting the image beam, intersects the first edge at a first point and the second edge at a second point. The distance between the first point and the second point corresponds to a specific location on a second axis. The alignment target may, as an example, be a right triangle where the first edge is the base of the right triangle and the second edge is the hypotenuse of the right triangle.
The alignment system measures the distance between the first point and the second point. Based on this distance, the alignment system is able to determine the transverse position of the image beam relative to the alignment target. The vertical position of the image beam may be referenced to the alignment target based on the location where the image beam intersects the first edge.